Intelligent transportation system, host processor, vehicle and method therefor

ABSTRACT

An intelligent transportation system (ITS) for a vehicle is described. The ITS includes: a packet count estimator arranged to receive broadcast ITS transmissions from a plurality of neighbouring vehicles and provide an indication of a number of packets received from the plurality of neighbouring vehicles, where the indication includes at least an information length and a data rate of the received packets; a fair resource allocator circuit operably coupled to the packet count estimator and configured to adjust at least one ITS broadcast transmission parameter of the ITS based on the indication of the number of received packets; and a transmitter operably coupled to the fair resource allocator circuit and configured to broadcast at least one ITS message using the adjusted at least one ITS broadcast transmission parameter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority under 35 U.S.C. § 119 of EuropeanPatent application no. 17169091.0, filed on 2 May 2017, the contents ofwhich are incorporated by reference herein.

FIELD OF THE INVENTION

The field of the invention relates to an intelligent transportationsystem (ITS), a host processor, a vehicle and a method therefor. Theinvention is applicable to, but not limited to, a mechanism toadaptively control a usage of resource when broadcasting ITS messages,and thereby control channel load, based on packet count.

BACKGROUND OF THE INVENTION

It is known that road usage by vehicles continues to increase, year onyear. Increased road usage causes many problems, such as increasedcongestion, longer travel time, higher travel costs, increased airpollution, increased accident risk, etc. In order to cope with thissteady increase, solutions are required to better manage vehicle roadusage. A possible solution is to construct new roads, which is unlikelyto happen on a large enough scale. A further solution is to reducetraffic and/or provide alternative transportation options, neither ofwhich is viable in most practical scenarios.

A further solution that is being widely researched and developed is theuse of intelligent traffic (or transportation) systems (ITSs). TheEuropean Commission Mobility & Transport Department reported that morethan one million traffic accidents have caused over 25,000 fatalities.As such, ITS has evolved to be a promising solution to improve trafficsafety. ITS is being developed for a variety of applications, such as astationary vehicle warning following an accident or vehicle problem,traffic condition warning (such as a traffic jam ahead warning),regulatory/contextual speed limits, road work warnings, detournotifications, etc. Some ITS solutions propose a communication backboneemploying V2X communication (i.e. a vehicle-to-vehicle infrastructure).

In ITS, broadcasting of real-time information of cars, e.g. theirpositions and speed, road conditions, events and accidents, is performedin a form of beacon messages via a Vehicular Ad-hoc NETwork (VANET)built on IEEE 802.11p and a dedicated short-range communication (DSRC).The broadcast information is received from neighbouring vehicles, andenables nodes (sometimes referred to as ITS stations) to create adynamic map of its neighbours and to some degree their operationalstatus. This dynamic map helps to track the ITS station's neighbours andpredict dangerous situations, thereby enabling various safetyapplications, as described in ‘Intelligent Transport Systems (ITS);Vehicular Communications; Basic Set of Applications; Definitions’authored by the European Telecommunications Standards Institute (ETSI)Intelligent Transport Systems (ITS), Tech. Rep., 2009. It is anticipatedthat future autonomous vehicles will require even higher level ofsafety, together with better supporting technologies in order to realizereliable safety applications.

Safety applications such as ITS require reliable communication in orderto satisfy various technical constraints, such as minimum message rateand range. Such technical constraints need to be satisfied by allnodes/ITS stations within the ‘awareness range’ of the application.Awareness range is defined as the minimum distance between the vehiclesat which the applications should predict a potential collision, suchthat the manoeuver of vehicles would avoid a potentially catastrophicaccident.

One known ITS station 100 is shown in FIG. 1 . ITS station 100 includesa wireless transceiver integrated circuit (TRx IC) 108 that compriseswireless transmitter and a wireless receiver connected to an antenna102. The receiver is arranged to receive ITS messages broadcast fromother local vehicles or fixed roadside units. The transmitter isarranged to broadcast ITS messages to other local vehicles or fixedroadside units.

The wireless TRx IC 108 is coupled to a baseband (BB) circuit 130, whichmay be of the form of a digital signal processor (DSP) and include, say,quadrature channel low pass filters (LPFs) and quadrature analog todigital converters ADCs functionality. Communication between thewireless TRx IC 108 and the BB circuit 130 may use the IEEE 802.11pcommunication protocol. The IEEE 802.11p is an update to the IEEE 802.11standard that adds wireless access in vehicular environments (WAVE),namely enhancements to 802.11 required to support ITS applications. Thisincludes data exchange between high-speed vehicles and between thevehicles and the roadside infrastructure in the licensed ITS band of 5.9GHz (5.85-5.925 GHz). IEEE 1609 is a higher layer standard based on theIEEE 802.11p. The BB circuit 130 typically performs the processing up toa data link layer (physical (PHY) layer and part of the medium accesscontrol (MAC) layer).

The system has a micro controller unit (MCU) 140 that is connected, via,say, a universal signal bus (USB) 138, to the BB circuit 130 thatexecutes a protocol 1609 stack, and thus converts IEEE1609 messages intoradio frequency (RF) signals for broadcasting. The MCU 140 is alsocoupled to a security circuit 150 that is used for signature generationfor IEEE 1609.2 messages. ITS 100 is thereby able to receive 802.11ppackets with messages from other vehicles, as well as transmit 802.11ppackets with messages to other vehicles. In the current scenario 802.11MAC would decide when a channel is free for it to broadcast the message.An ITS enabled vehicle broadcasts information to all other surroundingvehicles, which are similarly enabled. In this way, the surroundingvehicles can interrogate and process received ITS messages and build upan understanding of their surroundings vis-à-vis other vehicles or roadevents.

However, it is known that channel congestion is one of the most criticalissues in IEEE 802.11p-based vehicular ad-hoc networks becausecongestion may lead to unreliability of applications. As a countermeasure, ETSI proposed a mandatory Decentralized Congestion Control(DCC) framework to keep the channel load below a specific level in orderto avoid such congestion. DCC algorithms are therefore focused on tuningone or more operational parameters, such as transmit power, message-rateand data-rate, in order to avoid/limit congestion.

Most DCC algorithms are based on a parameter termed Channel Busy Ratio(CBR), which is a measure of the channel load that indicates a fractionof time that the channel is sensed as being ‘busy’ by a node/ITSstation. A CBR measurement is sufficient for a single data-rate network,so it is suitable for the proposed DSRC VANET, which uses only a default6 Mbps data rate for use by the ITS stations. Message-rate andtransmit-power based congestion control schemes try to maintain CBRbelow a channel load threshold (CBR_(T)) by decreasing either themessage-rate or the communication range, thereby reducing the load bymaintaining the same channel capacity. On the contrary, the data-ratebased approaches increase the channel capacity by transmitting packetsat higher data-rates and therefore in shorter transmission time, therebydisturbing channel capacity.

The inventors of the present invention have recognised and appreciatedthat CBR measurements are not able to measure the channel usageeffectively, particularly in networks that support multiple data-rates.This is primarily due to variation in collisions and propagation fadingin a wireless channel when multiple data rates are being employed. Theyhave further recognised and appreciated that the problem becomes worsein very high density mobile environments, for example as CBR onlyrepresents a fraction of time over which a channel is busy. Furthermore,when the inventors considered data-rate DCC functioning on CBRmeasurements alone, a channel with 10 packets at 6 Mbps and 20 Packetsat 12 Mbps may both have the same CBR. Thus, CBR doesn't provideaccurate information of channel load and varies depending on selecteddata-rate. Thus, two nearby nodes may be experiencing a CBR of, say,0.6, and may select 6 Mbps and 12 Mbps or even 24 Mbps data-rates touse, thereby leading to an unfair data-rate allocation among nodesexperiencing similar channel load conditions. To further explain thisproblem, let us consider a channel with packets transmitted at 6 Mbpsdata-rate with packet transmission time of 540 microseconds. In order tomaintain a CBR of 0.7 the maximum number of packets that the channel cansupport is 1296 packets. Similarly, if 12 Mbps is used with atransmission time of 360 microseconds in order to maintain a CBR of 0.7then the maximum number of packets that can be transmitted is increasedto 1944 because the channel capacity is increased. Thus CBR alone cannotprovide sufficient information regarding effective channel load and theresultant outcome is dependent on the data-rate selected.

This unfair allocation of data-rates will cause different nodes withsimilar channel activity to have different transmission ranges, and alsoadversely affect applications that are in need of reliable informationexchange. A suitable, fairer solution is desired.

SUMMARY OF THE INVENTION

The present invention provides an intelligent transportation system, ahost processor, a vehicle and a method therefor, as described in theaccompanying claims. Specific embodiments of the invention are set forthin the dependent claims. These and other aspects of the invention willbe apparent from and elucidated with reference to the embodimentsdescribed hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details, aspects and embodiments of the invention will bedescribed, by way of example only, with reference to the drawings. Inthe drawings, like reference numbers are used to identify like orfunctionally similar elements. Elements in the figures are illustratedfor simplicity and clarity and have not necessarily been drawn to scale.

FIG. 1 illustrates a simplified known block diagram of an intelligenttransportation system (ITS).

FIG. 2 illustrates a simplified diagram of a vehicle employing an ITSstation, adapted to control broadcast ITS messages, and thereby channelload, based on packet count, according to example embodiments of theinvention.

FIG. 3 illustrates a simplified first example block diagram of an ITSstation, adapted to control broadcast ITS messages, and thereby channelload, based on packet count, according to example embodiments of theinvention.

FIG. 4 illustrates a simplified second example block diagram of an ITSstation, adapted to control broadcast ITS messages, and thereby channelload, based on packet count, according to example embodiments of theinvention.

FIG. 5 illustrates a simplified example block diagram of a hostprocessor configured to support an ITS station adapted to controlbroadcast ITS messages, and thereby channel load, based on packet count,according to example embodiments of the invention.

FIG. 6 illustrates an example flow chart for controlling broadcast ITSmessages, and thereby channel load, in an intelligent transportationsystem and based on packet count, according to example embodiments ofthe invention.

DETAILED DESCRIPTION

The inventors of the present invention have recognized and appreciatedthat a mechanism to control broadcast ITS messages, and thereby channelload, in an intelligent transportation system and based on packet countwould be an improvement over the known use of CBR measurements, whichare not able to measure the channel usage effectively, due to e.g.collisions and propagation fading in a wireless channel. A packet-countapproach enables a fair-allocation of channel resources in order toimprove a fairness of a Decentralized Congestion Control (DCC)algorithm. In some examples, a fair-usage of channel resources may beimplemented in terms of adjusting one or more of: message rate,transmission power, data rate, in response to the determined packetcount. In some examples, the use of packet count based data rate(PDR)-DCC enforces a homogeneous data-rate selection amongst allvehicles, thereby providing fairness throughout the VANET.Advantageously, the packet count based channel load measurements alsoprovide a more accurate representation of channel load than CBR,irrespective of the data-rates, message-rate and transmit power that areprevalent, thereby reducing or eliminating the unfair data-rateallocation issue that exists in pure CBR based approaches.

In this manner, a packet count approach to assessing channel loadingaddresses a problem when channel capacity varies in responses todifferent supported data rates being used, and thus enables moreaccurate estimation of channel load to be determined. Examples of theinvention find applicability in networks that use multiple data rates,as the concepts herein described may improve the application reliabilityin heavy traffic situations, particularly when a data rate, from aplurality of selectable data rates, may be selected by the respectiveITS stations.

Aspects of the invention describe an intelligent transportation system(ITS), for a vehicle, a vehicle and a host processor configured tosupport ITS operations. The ITS, vehicle and/or host processor includesa packet count estimator arranged to receive broadcast ITS transmissionsfrom a plurality of neighbouring vehicles and provide an indication of anumber of packets received from the plurality of neighbouring vehicles,where the indication includes at least an information length and a datarate of the received packets; a fair resource allocator circuit operablycoupled to the packet count estimator and configured to adjust at leastone ITS broadcast transmission parameter of the ITS based on theindication of the number of received packets; and a transmitter operablycoupled to the fair resource allocator circuit (410) and configured tobroadcast at least one ITS message using the adjusted at least one ITSbroadcast transmission parameter. In this manner, the fair resourceallocator is able to adjust at least one ITS broadcast transmissionparameter based on a packet count estimate. Thus, a betterrepresentation of a channel load in an ITS may be achieved compared tothe known approach to use solely a CBR measurement.

In some examples, the packet count estimator may be configured toreceive physical layer information of the broadcast ITS transmissionsand determine therefrom the number of packets received from theplurality of neighbouring vehicles. In some examples, the at least oneITS broadcast transmission parameter may be from a group of:transmission data-rate, transmission message-rate, transmit power. Thepacket count is then used to schedule resource and allocate transmitterparameters in order to achieve a desired DCC.

In some examples, a channel busy ratio, CBR, circuit may be arranged tosense when a communication channel is being used to receive ITSinformation and provide an indication of a time that the channel is inuse, such that the packet count estimator may be configured to use theindication of time, together with the indication of at least aninformation length and a data rate of the received packets, in adetermination of a number of packets received from the, or each of the,plurality of neighbouring vehicles.

In some examples, a memory may be coupled to the fair resource allocatorcircuit and the packet count estimator and arranged to store at leastone of: packet count data, ITS broadcast transmission parameter data, anindication of at least an information length and a data rate of thereceived packets, wherein the fair resource allocator circuit may beconfigured to adjust at least one ITS broadcast transmission parameterof the ITS based on at least a portion of the stored data.

In some examples, the packet count estimation performed by packet countestimator may be based on a total of: packets sent, packets received,and a total number of packets sensed by the physical layer, while atleast the communication channel employed by the ITS is busy. In someexamples, the total packet count may be determined over a specified timeperiod (θ) and whilst the vehicle is not sending ITS packets.

In some examples, the ITS may be configured to provide an indication ofthe adjusted at least one ITS broadcast transmission parameter to avehicle to roadside (V2X) infrastructure or on a vehicle to vehicle(V2V) basis. In some examples, the ITS may support a plurality ofdifferent data rates and the fair resource allocator circuit switchesthe ITS broadcast transmission parameter between two of the plurality ofdifferent data rates based at least in part on the indication of thenumber of received packets.

In another aspect of the invention, a method for operating anintelligent transportation system, ITS, for a vehicle, is described. Themethod includes receiving broadcast ITS transmissions from a pluralityof neighbouring vehicles; providing an indication of a number of packetsreceived from the plurality of neighbouring vehicles, where theindication includes at least an information length and a data rate ofthe received packets; adjusting at least one ITS broadcast transmissionparameter of the ITS based on the indication of the number of receivedpackets; and broadcasting at least one ITS message using the adjusted atleast one ITS broadcast transmission parameter.

Referring now to FIG. 2 , a simplified diagram of a vehicle 200employing an ITS station 210, adapted to control broadcast ITS messages,and thereby channel load, based on packet count, is illustratedaccording to example embodiments of the invention. The ITS stationincludes a packet count estimator arranged to receive broadcast ITStransmissions from a plurality of neighbouring vehicles and provide anindication of a number of packets received from the plurality ofneighbouring vehicles, where the indication includes at least aninformation length and a data rate of the received packets; and a fairresource allocator circuit operably coupled to the packet countestimator and configured to adjust at least one ITS broadcasttransmission parameter of the ITS based on the indication of the numberof received packets. The ITS station further includes a transmitteroperably coupled to the fair resource allocator circuit and configuredto broadcast at least one ITS message using the adjusted at least oneITS broadcast transmission parameter.

In this example, the ITS station 210 comprises an MCU 240 operablycoupled to other circuits and components (not shown). The MCU 240 isoperably coupled to other components or circuits in the vehicle, e.g. aspeed sensor 250, via, say, an integrated communication bus network 220,such as a Controller Area Network (CAN or CAN-bus) or a LocalInterconnect Network (LIN). A CAN or CAN-bus is a vehicle bus standardthat is designed to allow microcontrollers and devices to communicatewith each other within a vehicle without a need for a host computer. LINis a serial network protocol used for communication between componentsin vehicles. In this example, the MCU 240 is adapted to control a datarate of broadcast ITS messages, and thereby channel load, based onpacket count as described below.

Although examples of the invention are described with reference to avehicle such as a car, as illustrated in FIG. 2 , it is envisaged thatany road transport device may use the concepts herein described, such astrucks, motorcycles, buses, etc.

Referring now to FIG. 3 , a simplified example block diagram of an ITSstation (ITS) 210, adapted to control a rate of broadcast ITS messages,and thereby channel load, based on packet count, is illustratedaccording to example embodiments of the invention. The ITS station 210includes a wireless transceiver integrated circuit 308 that comprises awireless transmitter and a wireless receiver connected to an antenna 302via an isolation component or circuit 304, which may be a duplex filteror antenna switch that isolates signals between the transmitter andreceiver circuits. In this example, the wireless transceiver integratedcircuit 308 is configured to operate at 2.4 GHz or 5.9 GHz.

One or more receiver chains, as known in the art, include(s) receiverfront-end circuitry 306 (effectively providing reception, low-noiseamplification, filtering and intermediate or base-band frequencyconversion). In example embodiments, the receiver receives a radiofrequency, RF, signal and converts the received RF signal to a digitalquadrature received signal. The receiver front end circuit 306, forexample, may comprise a low noise amplifier (LNA) coupled to twofrequency down-conversion quadrature mixers, fed from a quadrature localoscillator 326. The receiver front-end circuitry 306 is arranged toreceive ITS messages broadcast from other local vehicles or fixedroadside units.

In a transmitter chain sense, the transmitter comprises quadraturefrequency up-conversion circuit 322, which contains quadrature up-mixercircuit(s) and may contain amplification and additional filteringcircuits, arranged to up-convert differential quadrature signals 328from baseband (BB) circuit 330 which includes quadraturedigital-to-analog converters (DACs). The frequency up-conversion circuit322 combines the two resultant mixed quadrature signals before beinginput to power amplifier (PA) 324, which amplifies the combined signalprior to transmission. PA 324 outputs the up-converted and amplifiedtransmit signal to isolation component or circuit 304 and thereafterantenna 302. The transmitter is arranged to broadcast ITS messages toother local vehicles or fixed roadside units.

The receiver front end circuit 306 is also coupled to BB circuit 330,which may be of the form of a digital signal processor (DSP) andcomprise quadrature channel low pass filters (LPFs) and quadratureanalog to digital converters ADCs. Communication between the wirelesstransceiver integrated circuit 308 and the BB circuit 330 may use the802.11p communication protocol. The BB circuit 330 performs theprocessing up to a data link layer (physical (PHY) layer and part of themedium access control (MAC) layer). The ITS station 210 has amicrocontroller unit (MCU) 340, sometimes referred to hereafter as ahost processor, which is connected, via say a universal signal bus (USB)338 or SDIO or Ethernet interface, to the BB circuit 330. The BB circuit330 executes an IEEE1609 stack, and thus converts IEEE1609 messages intoRF signals for broadcasting. The MCU 340 includes a packet count circuit342 (or logic) configured to count a number of packets received bybroadcast transmissions from neighbouring vehicles.

In some examples, packet count circuit 342 calculates a packet count(P_(C)) for each data packet received from each neighbouring ITSstation/node, based on information received from the physical layercommunications. The total transmitted packets P_(T) at an ITSstation/node, and the total time taken or transmission T_(TX) over aperiod θ, can be obtained from this physical layer data. In someexamples, such a packet count is performed only when the channels issensed as being busy. In this example, there are three instances wherethe channel may be sensed as being ‘busy’, e.g. when: (i) the node istransmitting a packet; (ii) the node is receiving a packet; (iii) thenode is neither transmitting nor receiving, however the signal strengthis identified as being higher than a Carrier Sensing Threshold (CST),due to collisions, interference, etc.

The packets received at the physical layer of IEEE 802.11p consist ofpreamble, signal field and payload. The preamble field represents thebeginning of the frame and the signal field is used to specify thedata-rate and packet transmission time. In some examples, thisinformation is used to calculate the total number of packets that aresuccessfully sensed by the receiver (P_(R)) and the total time thechannel is sensed busy due to the reception at physical layer (T_(RX)).In order to obtain P_(B), the total number of packets and T_(BU), i.e.the total time during which the channel is busy while not able toreceive or transmit, some examples propose to utilize a CBR measurement,as illustrated in equation [1] and P_(B) may be obtained from a linearestimation over time (T_(BU)), such as Illustrated in equation [3]. Inthis example, the packet count (P_(C)) of the physical layer is obtainedfrom P_(T), P_(R) and P_(B), as illustrated in equation [2].T _(BU)=(CBR×θ)−(T _(TX) +T _(RX))  [1]P _(c) =P _(R) +P _(T) +P _(B)  [2]

Where:

-   -   P_(C) is the total packet count    -   P_(T) is the total number of transmitted packets;    -   P_(R) is the total number of packets successfully sensed by the        receiver; and    -   P₈ is the total number of packets during which the channel is        busy while not receiving or transmitting.        P _(B)=((P _(T) +P _(R))×T _(BU))/(T _(TX) +T _(RX))  [3]

It is envisaged in other examples that the P_(C) estimation may beperformed by various other approaches, such as machine learning,adaptive error correction, etc., in order to further improve accuracy.

The packet count circuit 342 is thus arranged to receive broadcast ITStransmissions from a plurality of neighbouring vehicles and provide anindication of a number of packets received from the plurality ofneighbouring vehicles, where the indication includes at least aninformation length and a data rate of the received packets. In thisexample, the packet count circuit 342 is coupled to a fair resourceallocator circuit 344, which in some examples may include a message datarate control circuit 344 configured to adjust at least one ITS broadcasttransmission parameter of the ITS, such as control a rate of broadcastITS messages, based on the indication of the number of received packets.The ITS station further includes a transmitter operably coupled to thefair resource allocator circuit 344 and configured to broadcast at leastone ITS message using the adjusted at least one ITS broadcasttransmission parameter.

Thus, in some examples, by obtaining physical layer information ofreceived packets, the packet count circuit 342 is able to calculate anumber of packets received from the plurality of neighbouring vehicles,based on at least the physical layer information of an informationlength and a data rate of the received packets. In some examples, theinformation may be derived from the packet length and modulation-codingscheme indicator in the physical layer signal field and packet header ofeach 802.11p packet. The packet count information is then utilized toselect a minimum possible data rate to avoid congestion and enablesmaximum possible range and reliability of safety applications.

In some examples, the MCU 340 may be configured to support multiple datarates for broadcast ITS transmissions and select a data rate for usebased on a determined packet count. If the MCU 340 determines, afterprocessing the packet count information, that the data rate of the ITStransmissions from the vehicle is to be reduced, the MCU 340 isconfigured to adapt the data rate of ITS messages that are broadcastfrom the vehicle, and vice versa.

Furthermore, in this manner and when employed in multiple vehicles, theITS application itself, within each of a majority or all of a number oflocalised vehicles, may be configured to intelligently decide on a datarate of messages (or another parameter associated with the ITStransmissions) that it is going to broadcast in a given time period. Inthis manner, a number of vehicles that are in a localised area and, say,moving slowly due to a traffic jam, may each increase the data rate ofITS messages that they broadcast, which will in turn not reduce too muchthe number of received ITS messages that they receive and process. Thevehicles use these ITS messages to calculate the positions of thevehicles around it. Therefore, even for a slow moving vehicle with aincrease data rate of messages it is still possible to calculate itsrelative position, vis-à-vis other vehicles in its vicinity.

In some instances, this decision may subsequently include dynamicallyvarying the data rate of messages sent by each vehicle proportional tothe determined packet count performed by each vehicle. When applied bymultiple vehicles, the data rate of messages that each vehicle needs toprocess is effectively impacted. Thereafter, for example and in responseto an adjustment of a data rate used for ITS transmissions inslow-moving traffic, it is envisaged that the vehicles create enoughchannel capacity to process, same number of messages/second irrespectiveof density.

In some examples, the host processor may be configured to maintain aminimum rate of messages/second to be sent out. In this manner, the hostprocessor ensures that other moving vehicles are informed about thevehicle's position. In some examples, the minimum rate ofmessages/second to be sent out may include any mandatory messages thatare to be sent, such as safety messages, e.g. a SOS message, a vehiclebreakdown message, a message following a crash, etc.

Referring now to FIG. 4 , a simplified second example of an ITS station,adapted to control broadcast ITS messages, and thereby channel load,based on packet count, is illustrated according to example embodimentsof the invention. In this example, a host processor, such as MCU 240from FIG. 2 or MCU 340 from FIG. 3 , is configured to perform a numberof ITS functions, but in this example the functionality for implementinga packet-count based DCC technique according to some examples of theinvention resides in stand-alone circuits or logic or processors coupledto the MCU 340.

In accordance with some examples, a packet count estimation processorcalculates a packet count for each received signal based on physicallayer information from a receiver (Rx) in, say, wireless TRx IC 308. Insome examples, depending upon how receiver senses the channel and thedata-rate information is present in the packet header itself is used tocalculate a total time taken by a packet. In some examples, noadditional information needs to be taken into account. In some examples,the packet count estimation may be based on a total number of packetssent, received, and a total number of packets sensed by the physicallayer, while the channel is busy, without the vehicle sending orreceiving a packet by a vehicle over a period θ. In some examples, thereare three cases where the channel is sensed as ‘busy’ that areconsidered in order to measure a total number of packets in the channel.The transmitted packets are also part of the channel load, thus they aretaken into account so that each ITS station can determine the correct orsuitable to transmit parameter(s) to use to broadcast ITS information.These measurements are performed based on various receiver (Rx) data andCBR measurements from CBR circuit 430.

In some examples, the packet count approach may be further improved byusing the measured history and environmental information, stored inmemory 440. For instance, if packets from a vehicle were counted in theprevious period, but not received in the current period, and the road isa closing highway and the vehicle is very-likely still in the range, thepacket count of the vehicle in the previous period can be factored intothe count in the current period. In some examples, sliding windowfiltering based on previous measured history can improve packet count.In some examples, such additional stored information may be useful whenthe channel does not have a good packet reception ratio and is heavilycongested (e.g. 95% or greater). The objective of PDR-DCC is to avoidcongestion (e.g. 70% or lesser), which further enables accurate packetcount measurements.

In this example, once a packet count is estimated the ITS station 400 isable to tune or adapt one or various parameters, such as message-rate,data-rate, and combine this strategy at the transmitter (TX) based onone or more DCC algorithm that is used, in order to avoid congestion. Inthis regard, host processor 410 is configured to determine and implementa fair resource allocation DCC and may also perform an ITS messagegeneration function that includes adaptively modifying a rate ofbroadcasting ITS messages to other vehicles. In some examples, hostprocessor 410 may adapt only the data-rate of broadcast ITS messages inresponse to the PDR-DCC determination. However, in other examples, it isenvisaged that other parameters, such as one or more of: message-rate,transmit power, etc. may be adapted in a similar manner.

In some examples, it is envisaged that the aforementioned packet counttechnique provides better information of channel load than CBR. Thepacket count estimation circuit 420 and host processor 410 thatimplements a fair resource allocation DCC may be based on how thephysical layer senses the channel and can be implemented without CBR.The packet count estimator 420 is configured to receive broadcast ITStransmissions from a plurality of neighbouring vehicles and provide anindication of a number of packets received from the plurality ofneighbouring vehicles, where the indication includes at least aninformation length and a data rate of the received packets. In someexamples, the described technique requires a knowledge of a total timethat the channel is busy without any transmission or reception (T_(BU)).However, as CBR information already exists (through it being mandated inthe Standard), some examples additionally use such CBR information toobtain the value of T_(BU) and thereafter use the packet countestimation circuit 420 to determine ITS broadcast transmissionparameter(s) to adapt.

In this example, the transceiver integrated circuit 308 and associatedbaseband circuitry may also perform V2x Wireless MAC layerfunctionality, for example consistent with European TelecommunicationStandards Institute (ETSI) ES 202 663 and in accordance with IEEE1609.4,In this example, the transceiver integrated circuit 308 and associatedbaseband circuit may also perform V2x Wireless physical (PHY) layerfunctionality, for example consistent with IEE802.11p, ETSI ES 202 663and in accordance with ISO21215. It is understood that the standardsthat are adopted around the World may very, and thus the examplesdescribed above, when employed in other implementations, may be replacedby similar technologies or Standard specifications other than IEEE1609.

Referring now to FIG. 5 , a simplified example block diagram 500 of ahost processor 510, configured to support an ITS application 520, isillustrated according to example embodiments of the invention. In theexample block diagram 500, the host processor 510 may be the main or subcontrol unit in the vehicle. In some examples, the host processor 510may have one or more micro controller units (MCUs), of which one of theMCUs might be configured to adaptively control a usage of resource whenbroadcasting ITS messages, and thereby control or influence channel loadin the system/VANET, based on packet count.

In this example, the host processor 510 includes a data acquisitioncircuit 530, which is operably coupled to a number of external circuits.For example, the data acquisition circuit 530 may be coupled to anemergency input circuit 532 configured to determine a vehicular crash,or a breakdown or heavy braking, etc. In some examples, the dataacquisition circuit 530 may be also coupled to a user interface circuit538, for example a human-machine interface (HMI), which is capable ofreceiving an SOS message or displaying information relayed fromemergency input circuit 532. In some examples, the host processor may beconfigured to process speed-related information from a speed-relatedsensor circuit 536, for example configured to provide vehicle speedand/or acceleration information to the host processor 510. In someexamples, the host processor may be configured to pass the informationto the user interface circuit 538 for displaying speed and/oracceleration data to a vehicle user (e.g. passenger or driver). In someexamples, the data acquisition circuit 530 of the host processor 510 maybe configured to process the speed-related information and providewarning information, say via an audible or visual warning, indicative ofsudden breaking of either the vehicle or surrounding vehicles.

In accordance with some examples, the data acquisition circuit 530 ofthe host processor 510 is operably coupled, via an input port 512, to aV2X (and/or a V2V) MAC and physical layer circuit 540, for exampleconfigured to handle transmission 542 and reception 544 of broadcast ITSmessages.

In this example, the data acquisition circuit 530 is coupled to the ITSapplication circuit 520, which in some examples includes a messagegeneration circuit 522, coupled to an intelligent message/data ratecontroller 526. In this example, the ITS application circuit 520 alsoincludes a fair resource allocator DCC circuit 552 arranged to determinewhether one or more ITS resource(s) needs to be changed and implementsuch a change when desired. In this example, such a change is based onthe information received from the packet count and CBR measurementcircuit 550, which in this example is located within data acquisitioncircuit 530.

Thus, packet count and CBR measurement circuit 550 is configured toreceive broadcast ITS transmissions from a plurality of neighbouringvehicles and provide an indication of a number of packets received fromthe plurality of neighbouring vehicles, where the indication includes atleast an information length and a data rate of the received packets.Fair resource allocator DCC circuit 552 is configured to adjust at leastone ITS broadcast transmission parameter of the ITS, based on theindication of a number of received packets.

In this manner, in one example, physical layer information obtainedfrom, say, V2X (and/or a V2V) MAC and physical layer circuit 540 isprocessed by the packet count and CBR measurement circuit 550 of dataacquisition circuit 530 and routed to the fair resource allocator DCCcircuit 552 of the ITS application circuit 520. Based on the packetcount information, the fair resource allocator DCC circuit 552 mayinfluence the intelligent message/data rate controller 526 to, say,adapt a data rate of ITS messages that are generated by messagegeneration circuit 522 and ultimately broadcast by the vehicle. In someexamples, the packet count information may include an indication of atleast an information length and a data rate of the received packets.Thus, in this example, the ITS application circuit 520 includes one ormore processing circuit(s) configured to process the received packetcount information and adapt a performance of the ITS of the vehicle inresponse thereto, e.g. reduce a data rate of ITS messages that aregenerated by the ITS message circuit 522 to be broadcast from thevehicle.

In some examples, the host processor may be configured to process thereceived packet count information and log the data in memory (notshown), so that the data, or the subsequent changes effected with one ormore resources, can be subsequently used by the vehicle's ITS station.

In some examples, the host processor may be configured to process thepacket count information and provide any information relating to a fairresource allocation amongst a number of ITS stations/vehicles to a V2Xinfrastructure, e.g. for monitoring and broadcast to all users forcentrally-controlled safety-related purposes.

Referring now to FIG. 6 , an example flow chart 600 illustrates a methodfor adaptively controlling a usage of resource when broadcasting ITSmessages, and thereby control of channel load, based on packet count,according to example embodiments of the invention. The flowchart 600starts with a vehicle at 602 with an ITS station capable of operating ina vehicle to vehicle (V2V) or vehicle to roadside infrastructure (V2X)mode of operation. At 603, the ITS station receives broadcast ITStransmissions from a plurality of neighbouring vehicles. At 604, the ITSstation initiates a packet count estimation mode of operation. In someexamples, the packet count estimation mode of operation at 604 mayobtain data from memory in 610. The packet count estimation may providean indication of a number of packets received from the plurality ofneighbouring vehicles, where the indication Includes at least aninformation length and a data rate of the received packets. At 606, adetermination is made, for example by a MCU, as to whether a resourceemployed with the ITS messages that are being broadcast should beadapted or changed based on the packet count. In this regard, in someexamples at 606 the determination is whether a fair resource adaption(e.g. of one or more of data-rate, message-rate, transmit power) may beneeded or may be beneficial to the ITS system (that includes multiplecommunicating ITS stations), as a whole. In some examples, thedetermination at 606 may also obtain data from memory in 610.

If the determination is that the resource(s) employed with the ITSmessages that are being broadcast should not be adapted or changed basedon the packet count, then at 612, at least one ITS message is broadcastusing the same (i.e. non-adjusted) at least one ITS broadcasttransmission parameter. The flowchart then loops back to 602. However,if the determination is that the resource(s) employed with the ITSmessages that are being broadcast should be adapted or changed based onthe packet count, then the flowchart moves to 608 where the one or moreresources are adapted based on the packet count. In some examples, theone or more resources may be increased or decreased at 608 by a fixedamount, or by an amount that is dependent upon the packet count. At 614,at least one ITS message is broadcast using the adjusted at least oneITS broadcast transmission parameter. The flowchart then loops to 602.In some examples, this change in resource may also be recorded in memory610.

In some examples, the circuits herein described may be implemented usingdiscrete components and circuits, whereas in other examples the circuitmay be formed in integrated form in an integrated circuit. Because theillustrated embodiments of the present invention may, for the most part,be implemented using electronic components and circuits known to thoseskilled in the art, details will not be explained in any greater extentthan that considered necessary as illustrated below, for theunderstanding and appreciation of the underlying concepts of the presentinvention and in order not to obfuscate or distract from the teachingsof the present invention.

A skilled artisan will appreciate that the level of integration ofprocessor circuits or components may be, in some instances,implementation-dependent. Furthermore, a single processor or MCU may beused to implement a processing of CBR information as well as performinga packet count of received ITS signals from other vehicles, as well assome or all of the other mentioned MCU functions. Clearly, the variouscomponents within the ITS can be realized in discrete or integratedcomponent form, with an ultimate structure therefore being anapplication-specific or design selection.

In the foregoing specification, the invention has been described withreference to specific examples of embodiments of the invention. It will,however, be evident that various modifications and changes may be madetherein without departing from the scope of the invention as set forthin the appended claims and that the claims are not limited to thespecific examples described above.

The connections as discussed herein may be any type of connectionsuitable to transfer signals from or to the respective nodes, units ordevices, for example via intermediate devices. Accordingly, unlessimplied or stated otherwise, the connections may for example be directconnections or indirect connections. The connections may be illustratedor described in reference to being a single connection, a plurality ofconnections, unidirectional connections, or bidirectional connections.However, different embodiments may vary the implementation of theconnections. For example, separate unidirectional connections may beused rather than bidirectional connections and vice versa. Also,plurality of connections may be replaced with a single connection thattransfers multiple signals serially or in a time multiplexed manner.Likewise, single connections carrying multiple signals may be separatedout into various different connections carrying subsets of thesesignals. Therefore, many options exist for transferring signals.

Those skilled in the art will recognize that the architectures depictedherein are merely exemplary, and that in fact many other architecturescan be implemented which achieve the same functionality.

Any arrangement of components to achieve the same functionality iseffectively ‘associated’ such that the desired functionality isachieved. Hence, any two components herein combined to achieve aparticular functionality can be seen as ‘associated with’ each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermediary components. Likewise, any two componentsso associated can also be viewed as being ‘operably connected,’ or‘operably coupled,’ to each other to achieve the desired functionality.

Furthermore, those skilled in the art will recognize that boundariesbetween the above described operations merely illustrative. The multipleoperations may be combined into a single operation, a single operationmay be distributed in additional operations and operations may beexecuted at least partially overlapping in time. Moreover, alternativeembodiments may include multiple instances of a particular operation,and the order of operations may be altered in various other embodiments.

Also for example, in one embodiment, the illustrated examples may beimplemented as circuitry located on a single integrated circuit orwithin a same device. For example, the host processor for an intelligenttransportation system, ITS, for a vehicle, may be implemented ascircuitry located on a single integrated circuit. Here, the hostprocessor circuitry comprises an input port for operably coupling to aspeed sensor; and a processing circuit configured to process the speedinformation received from the speed sensor and adapt a performance ofthe ITS of the vehicle in response thereto. Alternatively, the circuitand/or component examples may be implemented as any number of separateintegrated circuits or separate devices interconnected with each otherin a suitable manner. Also for example, the examples, or portionsthereof, may implemented as soft or code representations of physicalcircuitry or of logical representations convertible into physicalcircuitry, such as in a hardware description language of any appropriatetype. Also, the invention is not limited to physical devices or unitsimplemented in non-programmable hardware but can also be applied inprogrammable devices or units able to perform the desired packetcounting and processing by operating in accordance with suitable programcode, such as minicomputers, personal computers, automotive and otherembedded systems, cell phones and various other wireless devices,commonly denoted in this application as ‘computer systems’. However,other modifications, variations and alternatives are also possible. Thespecifications and drawings are, accordingly, to be regarded in anillustrative rather than in a restrictive sense.

In the claims, any reference signs placed between parentheses shall notbe construed as limiting the claim. The word ‘comprising’ does notexclude the presence of other elements or steps then those listed in aclaim. Furthermore, the terms ‘a’ or ‘an,’ as used herein, are definedas one, or more than one. Also, the use of introductory phrases such as‘at least one’ and ‘one or more’ in the claims should not be construedto imply that the introduction of another claim element by theindefinite articles ‘a’ or ‘an’ limits any particular claim containingsuch introduced claim element to inventions containing only one suchelement, even when the same claim includes the introductory phrases ‘oneor more’ or ‘at least one’ and indefinite articles such as ‘a’ or ‘an.’The same holds true for the use of definite articles. Unless statedotherwise, terms such as ‘first’ and ‘second’ are used to arbitrarilydistinguish between the elements such terms describe. Thus, these termsare not necessarily intended to indicate temporal or otherprioritization of such elements. The mere fact that certain measures arerecited in mutually different claims does not indicate that acombination of these measures cannot be used to advantage.

What is claimed is:
 1. An intelligent transportation system (ITS) for avehicle, the ITS comprising: a packet count estimator arranged toreceive broadcast ITS transmissions from a plurality of neighboringvehicles and provide an indication of a number of packets received fromthe plurality of neighboring vehicles, where the indication includes atleast an information length and a data rate of the received packetsbased on a total time a communication channel is busy; a fair resourceallocator circuit operably coupled to the packet count estimator andconfigured to improve fairness in allocation of channel resources forthe broadcast ITS transmissions by adjusting at least one ITS broadcasttransmission parameter of the ITS based on the indication of the numberof received packets; and a transmitter operably coupled to the fairresource allocator circuit and configured to broadcast at least one ITSmessage to neighboring vehicles using the adjusted at least one ITSbroadcast transmission parameter.
 2. The ITS of claim 1 wherein thepacket count estimator is configured to receive physical layerinformation of the broadcast ITS transmissions and determine therefromthe number of packets received from the plurality of neighboringvehicles.
 3. The ITS of claim 1 wherein the at least one ITS broadcasttransmission parameter is from a group of: transmission data-rate,transmission message-rate, transmit power.
 4. The ITS of claim 1 furthercomprising a channel busy ratio (CBR) circuit arranged to sense when thecommunication channel is being used to receive ITS information andprovide an indication of a time that the channel is in use, wherein thepacket count estimator is configured to use the indication of the time,together with the indication of at least an information length and adata rate of the received packets, in a determination of a number ofpackets received from the, or each of the, plurality of neighboringvehicles.
 5. The ITS of claim 1 further comprising a memory coupled tothe fair resource allocator circuit and the packet count estimator andarranged to store at least one of: packet count data, ITS broadcasttransmission parameter data, an indication of at least an informationlength and a data rate of the received packets, wherein the fairresource allocator circuit is configured to adjust at least one ITSbroadcast transmission parameter of the ITS based on at least a portionof the stored data.
 6. The ITS of claim 1, wherein the packet countestimator is configured to perform a packet count estimation based on atotal of: packets sent, packets received, and a total number of packetssensed, while at least one communication channel employed by the ITS isbusy.
 7. The ITS of claim 6, wherein the total packet count isdetermined over a specified time period (θ) while the vehicle is notsending ITS packets.
 8. The ITS of claim 1 further comprising amicrocontroller or a host processor configured to include the fairresource allocator circuit and the packet count estimator.
 9. The ITS ofclaim 8 wherein the microcontroller or the host processor is configuredto provide an indication of the adjusted at least one ITS broadcasttransmission parameter to a vehicle to roadside (V2X) infrastructure oron a vehicle to vehicle (V2V) basis.
 10. The ITS of claim 1 wherein theITS is configured to support a plurality of different data rates and thefair resource allocator circuit switches the ITS broadcast transmissionparameter between two of the plurality of different data rates based onat least in part the indication of the number of received packets.
 11. Ahost processor for an intelligent transportation system (ITS) for avehicle, the host processor comprising: a packet count estimatorarranged to receive broadcast ITS transmissions from a plurality ofneighboring vehicles and provide an indication of a number of packetsreceived from the plurality of neighboring vehicles, where theindication includes at least an information length and a data rate ofthe received packets based on a total time a communication channel isbusy; and a fair resource allocator circuit operably coupled to thepacket count estimator and configured to adjust at least one ITSbroadcast transmission parameter of the ITS for ITS broadcasttransmissions, based on the indication of a number of received packets.12. A method for operating an intelligent transportation system (ITS)for a vehicle, the method comprising: receiving broadcast ITStransmissions from a plurality of neighboring vehicles over acommunication medium; via a packet count estimation circuit, providingan indication of a number of packets received from the plurality ofneighboring vehicles, where the indication includes at least aninformation length and a data rate of the received packets based on atotal time the communication medium is busy; allocating use of thecommunication medium by the ITS by adjusting at least one ITS broadcasttransmission parameter of the ITS based on the indication of the numberof received packets; and broadcasting at least one ITS message toneighboring ITS systems over the communication medium using the adjustedat least one ITS broadcast transmission parameter.
 13. The hostprocessor of claim 11 further comprising: a transmitter operably coupledto the fair resource allocator circuit and configured to broadcast atleast one ITS message to neighboring ITS systems using the adjusted atleast one ITS broadcast transmission parameter.
 14. The host processorof claim 11 wherein the packet count estimator is configured to receivephysical layer information of the broadcast ITS transmissions anddetermine therefrom the number of packets received from the plurality ofneighboring vehicles.
 15. The host processor of claim 14 wherein the atleast one ITS broadcast transmission parameter is from a group of:transmission data-rate, transmission message-rate, transmit power. 16.The host processor of claim 14 further comprising a memory coupled tothe fair resource allocator circuit and the packet count estimator andarranged to store data including at least one of: packet count data, ITSbroadcast transmission parameter data, an indication of at least aninformation length and a data rate of the received packets, wherein thefair resource allocator circuit is configured to adjust at least one ITSbroadcast transmission parameter of the ITS based on at least a portionof the stored data.
 17. The host processor of claim 14 wherein the hostprocessor is configured to provide an indication of the adjusted atleast one ITS broadcast transmission parameter to a vehicle to roadside(V2X) infrastructure or on a vehicle to vehicle (V2V) basis.
 18. Thehost processor of claim 14 wherein the ITS supports a plurality ofdifferent data rates and the fair resource allocator circuit switchesthe ITS broadcast transmission parameter between two of the plurality ofdifferent data rates based on at least in part the indication of thenumber of received packets.
 19. The host processor of claim 11 furthercomprising a channel busy ratio, CBR, circuit arranged to sense when thecommunication channel is being used to receive ITS information andprovide an indication of a time that the channel is in use, wherein thepacket count estimator is configured to use the indication of the time,together with the indication of at least an information length and adata rate of the received packets, in a determination of a number ofpackets received from the, or each of the, plurality of neighboringvehicles.
 20. The host processor of claim 11 wherein a packet countestimation performed by packet count estimator is based on a total of:packets sent, packets received, and a total number of packets sensed,while at least one communication channel employed by ITS is busy.